Nelson Irrigation Corp. 848 Airport Rd. Walla Walla, WA 99362-2271 USA Tel: 509.525.7660 Fax: 509.525.7907 E-mail: info@nelsonirrigation.com Web site: www.nelsonirrigation.com
MR/MRDC
MDC Guide
OPERATION DETAILS
3.0 OPERATION DETAILS
All models of the regulator work the same while regulating. The difference between the options is in the
check operation. This cut-away drawing shows how the regulator and the check works.
3.1 MR (MINI REGULATOR)
The MR regulator will allow water flow but does not provide any pressure control benefit until the rated inlet
pressure is provided. Any additional pressure is then regulated to keep the irrigation constant. Provide a 5
PSI pressure margin to have the most accurate pressure regulation.
3.2 MRDC/MDC DRAIN CHECK FUNCTION
The check will not open until minimum pressure is provided to the base of the MRDC and MDC. Minimum
pressure to open is approximately 13 psi below rated pressure. For the MRDC, exact regulation will not
take place until the minimum inlet pressure is reached. Provide an additional 5 psi pressure margin to
have the most accurate pressure regulation. The MRDC and MDC work the same but the MDC does not
regulate pressure.
3.3 LOW TEMPERATURE CAUTION
The MRDC and MDC are not designed for operation below freezing. Remove the MRDC or MDC and drain
the irrigation pipes during freezing conditions otherwise ice can damage the system. THIS PRODUCT IS
NOT RECOMMENDED FOR USE IN FREEZING CONDITIONS.
MRDC AND MDC
FUNCTION AS
A CHECK (NO FLOW)
MR AND MRDC OPERATING AS
A REGULATOR (REGULATED
FLOW) - THE MDC WILL BE FULLY
OPEN BUT DOES NO PRESSURE
REGULATION
regulated pressure
3
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